How To Keep Your Car Battery Charged When Not In Use?

Methods of staying a vehicle battery alive.

It’s the time of the year again when the temperature goes negative, and it becomes difficult for everyone to go outside let alone drive out in the snow. Have you ever tried to ask yourself, how to keep car battery charged when not in use?

It usually takes about 12 hours to fully charge a battery with a big 400 to 500 cold cranking amps with a battery voltage that is below 11.85 and a 5-amp charge rate.

Yes, it takes so much time that’s why it’s always a question of ‘how’ to minimize the tendency of losing its charge during winter – with at least 20%.

Most of the time, the main reason why a car is stuck is that of the temperature outside. Now, the question is, how to keep car battery charged when the temperature is colder than usual?

There are three possible solutions that you can do to keep your car battery charged even if you are staying the whole month indoors and technically, not using your cars.

First, keep your car in the garage.

Second, keep your car batteries away from corrosion.

Lastly, get your battery checked at least month before the colder season hits your city.

3 Ways To Keep Your Car Battery Alive For Cold Winter

1. Keep your car in the garage and secure your battery.

Probably the most evident reason why you need to park your car inside the garage is that when snow, wind, and other climate components strike in, it can damage your car – specifically your battery.

A car battery functions better during summer because of the warm temperature apart from the other season in a year when it is colder. Have you ever felt being slapped by cold wind right in your face? Then you might have an idea of how chilling it is for a car battery to be left alone outside your house.

If your house doesn’t have a garage, you can park the front of the car away from the main direction of the wind.

2. Keep your car batteries away from corrosion.

Make sure that the terminals of your car battery are free of any elements that can cause spoilage. If you see a white powder around those terminals that resemble dead skin on your winter hands, at that point, this is an indication of corrosion. Low temperature can trigger dirt and other things to get inside the battery terminals, so you need to make sure that it is clean.

You can clean the battery busing a damp cloth with a baking soda, water, and a toothbrush that you are not using anymore. In some accounts, they apply petroleum jelly on the terminals which help prevent corrosion that makes the battery survive the long cold winter.

One perfect example of a wrong battery terminal due to dirt present into it is corrosion. Dirt that is present can stop the battery terminals to send power and in some worst cases, can result in a more severe problem which is the loss of electrical power. Thus, making it a little bit difficult to start the car’s engine.

Read this article if you need to clean your battery terminals.

3. Make sure to get your battery checked at least month before the colder season hits your city.

A car battery lasts for an average of four years. In testing your car battery’s health, you can use a multimeter to see if it has enough charge or not. Once you turn on the headlights, at 80°F, the voltage drop should be at least 11.8 volts (that is 252% charged), and ideally 12.5 volts, between both positive and negative terminals.

Also, if you want to see the specific gravity of the liquid inside it, you can use the hydrometer. The severity of the fluid should be between 1.265 and 1.299.

Related questions

Q1. What are the things that can drain your car batteries?

Different things might be a reason why your car batteries easily drain without even if you are not using the car.

Parasitic Drain

There are car components that continue to run even if you turn off the vehicle. The clock, the radio presets, and yes, the security alarm. These things keep on working even if your car is not moving. It is normal.

However, you also have to check if there are no faulty wiring and defective fuses inside your engine that can contribute to what is normal – and can drain the battery faster than you have expected.

Defective Alternator

The car alternator is the one that is responsible for recharging the battery and supply power to the lights, radio, air-conditioning, and automatic windows. If the car alternator is faulty, it is no wonder that your battery can drain.

You will notice that the engine will shut off and the engine won’t start. If it does happen, it most likely because the alternator has a bad diode.

Old Battery

If a car battery is old, it will no longer hold a full charge well. If your battery is old or weak, it will not hold a full charge well. One thing to find out if your battery is already worn out is when your vehicle regularly won’t start.

A cell can last for an average of 3-4 years only. You need to replace it every four years to avoid other issues.

Q2. Can a bad alternator ruin a new battery?

Yes. A defective alternator can kill a new battery. You will discover that the alternator is faulty when you tried to run the car and unplug the positive connection of the battery. If the car stops when you did that, then the problem lies with the alternator.

When it pains to know that a newly bought battery can be damaged because of faulty diodes, we also need to know what causes it to malfunction.

Here are some of the reasons why they tend to lose their spark:

• Defective connection between the alternator and the car battery (it could be broken cables, open circuits, and corrosion that has been developed over time).
• Human error. Sometimes, we are not aware that we are doing the wrong thing especially when changing batteries while the engine is running. This a red flag.
• Excessive surge of power can burn out the electrical devices called diodes in the vehicle causing the car not to start.

Q3. What to do with a battery that keeps dying even if it’s new?

Since there is a thing we called parasitic drain, we also need to pay attention to that. We suggest that you find the car’s fuse box, remove the cover and take a photo of the actual thing that is going on inside so you know which can be having a problem. You could ask for a mechanic’s help if you didn’t know how to fix the problem.

Most of the time, the problem lies with a bad or defective alternator. A damaged diode is the usual reason for the failure. These diodes are a piece of the rectifier that has been assembled to help convert the alternator’s AC yield to DC. The higher the charging load, the hotter it can get.

Your standard driving scenarios and charging loads won’t be a worry and surely won’t burn out these electrical device. However, infrequent driving can significantly shorten the life of these diodes. You have to make sure that these are always in a good condition.

Aside from faulty diodes, a malfunctioning voltage regulator can cause charging problems and may contribute to shortening the battery’s life even if it’s new. Some older model of vehicles have their external voltage regulators; however, the newer ones use the PCM (Powertrain Control Module) to control the charging output.

You can identify alternator problems by conducting a bench test. A bench test will check the diodes and the internal regulators and let you know if the alternator is capable of producing its rated current and voltage. If it fails, you need to replace your alternator.

However, if none of the test mentioned above fails, then the problems lie somewhere else. You have to check the wiring or connector or the PCM control circuit. If the fault lies on the PCM control circuit, then it should be replaced.

Once the PCM has been restored, the battery can be reconnected as well. However, this PCM should undergo a “relearning” process for it to function alongside the car’s battery.


There are different ways on how to keep a car battery charged when not in use. However, it doesn’t assure you that there will be no slight changes in the battery’s life especially during the winter season that cars are mostly staying in the garage.

Here are some points to remember:

• Assess the age of your car’s battery. It is essential to know if your battery is new or quite a few years old.
• Make sure that there is no corrosion, dirt or even little debris that might result in a more serious problem later on.
• Install a battery blanket. It is used to wrap around the battery to fit inside the battery cover. A battery blanket could produce enough heat needed by the cell during cold winter days. (Find out more about it).
• Disconnect the battery. You can disconnect the battery if you are going to store your car in the garage for an extended period. Or you have no plans of going out, or the weather doesn’t permit you to do so, you can remove the battery as clocks and other devices in the car such as alarm systems drain battery power even if you are not using the car. (Check the related article here).